topic 1 orgs

Question 1

what is a population?

Answer 1

a population is a group of individuals of a species that occur together at the same place and time.

Question 2

what are the 4 types of evidence that supports the theory of evolution by natural selection

Answer 2

• fossils
• the anatomical record
• genetic sequences
• selection experiments/ observations

Question 3

what does the term vestigial mean?

Answer 3

organ or part of the body which has become functionless in the course of evolution

Question 4

what are homologous structures?

Answer 4

homologous structures have a different appearance among species but derive from the same body part in a shared ancestor

Question 5

what are the modes of selection (3)

Answer 5

directional selection

stabilising selection

disruptive selection

Question 6

what are the sources of variation?

Answer 6

sexual recombination (genes from both parents)

mutation

gene flow (movement of organisms from one place to another.

Question 7

how do species arise?

Answer 7

they arise through evolution

Question 8

what is the difference between analogous traits and homologous traits?

Answer 8

homologous traits are traits that are shared between species, e.g the limbs of a human and cat are the same but have evolved in different ways

analogous traits are similar traits but are not related to each other eg flying in a bird compared to a moth, two different structures.

Question 9

what does fitness refer to?

Answer 9

fitness refers to the combined effects of survival and reproduction on the growth of a population

Question 10

what does natural selection do in terms of genes frequency?

Answer 10

natura selection effects the frequency of genes in a population through its effects on the survival and reproduction of individuals that have different genotypes

Question 11

what is adaptation?

Answer 11

adaptation is an inherited characteristic of an organism that enhances its survival and reproduction in specific environments

it is a continuous process

Question 12

what is genetic drift?

Answer 12

random changes in a gene frequency, important in small populations

Question 13

what are the two steps of speciation ?

Answer 13

1. the characteristics of initially identical populations must diverge
2. reproductive isolation must evolve to maintain differences

eg a lake that dries up in the middle and one side the fish become blue and the other remain red.

Question 14

what is alopatry?

Answer 14

populations occur in seperate locations with a barrier between them

Question 15

what is sex?

Answer 15

the coming together of genetic material from two parents to form progeny that combines genes from both of them

Question 16

what do females look for in males?

Answer 16

females choose based on male traits and signals that are indicators of fitness

Question 17

what is runaway sexual selection

Answer 17

even if there are negative effects associated with the male trait, women will still select the males with the negative trait, eg peacocks with more spots get chosen by females more despite it being more prone to predation. This trait only stays if gains in reproduction out weigh losses in survival

Question 18

what are archaea

Answer 18

ancient bacteria

single celled organisms that lack a nucleus

can inhabit extreme environments

Question 19

what are bacteria

Answer 19

most abundant organisms on earth

simple single celled organisms that lack a nucleus

Question 20

eukarya

Answer 20

the ancestral eukaryotic cell probably had a nuclues

mitochondria were acquires as a endosymbiotic photosynthetic bacteria

Question 21

what are some characteristics of fungi

Answer 21

heterotrophic - obtain nutrients from the environment

fiamentous strucutres - bodies are up of hyphae

cell walls composed of chiting

store glycogen - not starch

thought to have evolved from an aquatic flagellum bearing single celled organism

Question 22

what does symbiosis and mutualistic mean

Answer 22

symbiosis = living together

mutualistic = beneficial to both partners